The present invention relates to a leaktight container for packaging a liquid, including a sheet fixed to the internal face of a wall of the container by a leaktight connection surrounding a region of this sheet thus isolating it from the inside of the container, the breaking of this sheet in the said region thus isolated allowing access to the inside of the container.
Such leaktight containers with more or less solid flexible walls, pierced with an opening which is sealed by a membrane fixed against its internal face, and used for the packaging of liquid are already known. To access the inside of the container, all that is required is for the membrane to be pierced. In general, when the liquid is a drink, the membrane is pierced using a drinking straw which is then used for sucking up the liquid. When the container is a flexible-walled bag in particular, the pressure required to pierce the membrane is transmitted to the wall of the bag, thus temporarily increasing the pressure on its liquid contents at the moment it is being opened, this meaning that the pressurized liquid can come out of the bag.
DE-A1-41 15 000 discloses a tubular bag in which the border parts adjacent to the longitudinal edges overlap, each of these edges being welded to the adjacent face. An opening is made in the border part of the underlying longitudinal edge, while a tab, which is offset with respect to the opening, is cut in the border part of the longitudinal edge covering this underlying part. A transverse weld extends between the two welded longitudinal edges. This transverse weld passes between the opening and the tab, so that a leaktight barrier isolates this opening from the cut out tab. To open the bag, it is merely necessary to pull on this tab so as to tear that portion of the wall of the bag which covers the opening.
To access the opening, the transverse weld which separates the opening from the tab must first of all be broken by pulling this tab. This breaking of this transverse weld requires substantial effort. It is also difficult to control. This means that there is a risk of it""s either causing the tab to break, or of the longitudinal welds becoming torn, causing the bag to fall apart. Independently of these risks, the leaktight overlap region in which the opening is located, situated between the longitudinal welds, the transverse weld and a weld sealing one end of the bag, is in communication with the inside of the bag. This means that liquid can enter this region. As the bag is being opened, this liquid may run out over the external face of the bag and dirty it.
Leaktight bags are also known which have a valve, at least part of which is situated inside the bag and is formed between two flexible sheets passing through part of the bag and fixed in leaktight fashion between the edges of the bag. These sheets are joined together along two lines which do not converge so that by moving the said sheets away from one another a passage is formed between these lines, allowing a fluid to pass from the inside to the outside of the bag, the flexible sheets being intended to be pressed one against the other as soon as a force for parting them is no longer applied to them, thus preventing the said fluid from coming out of the bag.
Such bags are known and have been described in WO 985/23742, in FR 2 711 115 or in FR 1 338 549 in particular.
The valve of these leaktight bags is normally formed by a passage which is open at both of its ends which means that it offers the user no guarantee regarding use of this bag prior to its purchase. Aside from the fact that the purchaser therefore has no guarantee that the bag still contains the initially packaged amount of product, neither does he have any guarantee regarding the conditions of hygiene of the product thus packaged.
To overcome this drawback, it has been proposed to seal one of the ends of the passage using an attached cap, thus requiring another component to be added to the packaging.
To work effectively, the passage forming the valve between the two flexible sheets has to be long enough to provide an effective seal. In the solutions proposed hitherto, the length of the passage has been increased by forming a passage which is at an angle to the major axis of the bag, which means that the length of this passage is increased without a proportionate increase in the length of the flexible sheets extending into the bag. All the same, the surface area of flexible sheet used is substantially greater than the surface area occupied by the passage.
In addition to optimum usage of the sheet material forming the valve, one of the objects of the present invention is optimum usage of the volume of the bag. In bags of the state of the art, the top of the bag is left open to allow for filling. The fill level cannot be very high in such cases otherwise the liquid overflows from the bag when the top edge is welded up. This means that the extent to which the liquid fills the bag is not very high. Of course it is possible to fill the bag through the passage of the valve, but liquid would remain in this passage, and this would not be acceptable as the passage has to remain perfectly clean until it is first used.
The object of the present invention is to overcome, at least in part, the aforementioned drawbacks.
To this end, the subject of the present invention is a leaktight container in which a tab, intended for opening the said container, is formed in the portion of its wall adjacent to a region of the sheet fixed to the inside of the container, surrounded by a leaktight connection attaching this sheet to the wall of the container, one end of this tab being free and acting as a means for holding, while another part of this tab is fixed to the said sheet, thus allowing the said sheet to be broken by pulling on the tab and thus gaining access to the inside of the container.
Another subject of this invention is a leaktight bag of the aforementioned type, fitted with a valve. To this end, a second flexible sheet is joined to the first sheet, which is also flexible, along two connection lines which do not converge extending between two distant parts of the joined-together edges of the walls of the container to form a passage between these sheets in the part extending between the connection lines, at least one of the said sheets having a cut between the said non-converging connection lines, some distance from the said leaktight connection between the said first sheet and the wall of the container so as to make the said passage communicate with the inside of the container, the parts of these sheets situated between the said connection lines being intended to be pressed one against the other as soon as a force for parting them is no longer applied to them, thus preventing the said fluid from coming out of the container after an opening has been made in the said first sheet using the said tab.
Another subject of the invention is a bag or a leaktight container of the aforementioned type, fitted with a valve, in which bag or container a second passage is formed between the said flexible sheets and has an outer end adjacent to one edge of the said bag and the other end in communication with the inside of this bag.
Another subject of this invention is a method for packaging a liquid in a bag or container including the said second passage, according to which method the bag together with the two passages is formed, at least the outer end of the said second passage adjacent to the edge of the said bag is left open, the said liquid is introduced through this second passage and the said outer end of the second passage is sealed.
Among the many advantages of the container which forms the subject of the present invention, in the case of a valveless container, apart from the fact that it overcomes the risk of liquid under pressure leaking out as this container is being opened, the solution proposed does not add any additional components to the leaktight container as compared with the known solutions, the tab being formed by a portion of the wall of the container. This solution therefore does not lead to an increase in production costs. Furthermore, existing production lines can continue to be used with only very slight modifications affording an advantage which is not insignificant from the product standpoint.
In the container with a valve, the valve is protected from any attempts at tampering. Hygienic conditions are perfectly guaranteed right up to the first time that the bag is used. The number of components forming the bag and the valve are reduced as far as possible, no attached element being needed to tamperproof the valve. The area of sheet needed to produce the passage and the fillable volume of the bag is optimized.
Other advantages will emerge from reading the description which follows, given with the aid of the appended drawing which illustrates, diagrammatically and by way of example, one embodiment and various alternative forms of the leaktight container which forms the subject of this invention.